A system administrator doesn't bother with GUIs. He types commands at the command line and likes data displayed in the cmd.exe window. But, sometimes an administrator needs a "utility" like Microsoft Excel.
If you want to script Excel you need to know the Excel object model documentation.
This website provides a brief overview of commonly used objects in the Microsoft Office Excel 2003 object model and examples of using those objects to perform tasks: Automating Excel Using the Excel Object Model.